What is the legal test for dismissing a motion for lack of prosecution?

However, "[d]ismissal is a harsh penalty and is to be imposed only in extreme circumstances." Henderson v. Duncan, 779 F.2d 1421, 1423 (9th Cir. 1986). A court must weigh several factors in determining whether to dismiss for lack of prosecution: "(1) the public's interest in expeditious resolution of litigation; (2) the court's need to manage its docket; (3) the risk of prejudice to the defendants; (4) the public policy favoring disposition of cases on their merits and (5) the availability of less drastic sanctions." Id.